Nuclear magnetic resonance and nuclear quadrupole resonance studies of Ni-61 in heavy fermion compounds Ce7Ni3

The heavy fermion compound Ce7Ni3 is an antiferromagnet with T(N)similar to 1.7 K. According to the high pressure experiment, this compound has underg one a transition to a non-Fermi liquid state at similar to 0.32 GPa and has recovered a Fermi liquid state at similar to 0.62 GPa again. Before the hi gh pressure nuclear magnetic resonance (NMR) study through two transitions, we have performed NMR experiments of Ni-61, Co-59 and Cu-63 in order to cl arify the electronic states at ambient pressure. Two kinds of partially ove rlapping Ni NMR spectra were observed in Ce7Ni3 containing an enriched Ni-6 1. This result may be ascribed to two intrinsic local fields presumably due to the lattice distortion, etc. All the relaxation rates studied here are proportional to temperature above 1.4 K in the paramagnetic state, which in dicates that the systems are in the Fermi liquid state at ambient pressure. The increase of (1/T1T) with increasing Co concentration, C-Co, tells us t hat the partial density of states on Ni-3d states at Fermi level, N(E-F)(Ni ), increase with C-Co. On the contrary, C-Cu-independent (1/T1T) values ind icate N(E-F)(Ni) keep almost constant with Cu doping. (C) 2000 American Ins titute of Physics. [S0021-8979(00)64908-3].